Salt and Pepper the chicken breasts, and then dust the chicken in the flour to coat lightly.
In a large heavy frying pan, heat the oil over a medium-high heat.
Add the chicken pieces to the pan and cook until lightly brown, about 5 minutes per side. If all the chicken do not fit in the pan, brown them in 2 batches. Transfer the chicken to a plate and set aside.
Add the bell pepper and onion to the same pan and saute over medium heat until the onion is tender, about 4 minutes. Add the garlic and saute 1 more minute. Season the vegetables with salt and pepper.
Add the wine and simmer until reduced by half, about 3-4 minutes and then add the tomatoes with their juice, chicken stock, and oregano.
Return the chicken to the pan and turn them to coat in the sauce. Bring the sauce to a simmer. Continue simmering over medium-low heat until the chicken is cooked through, about 30 minutes. Taste to adjust the salt and pepper to your tastes. Top with basil and serve.
Can be served over rice as well.